Formwork for the inside surface of a wall structure confining a vertical opening



July 20, 1965 F. HOFMANN 3,195,851 FORMWORK FOR THE INSIDE SURFACE OF A WALL STRUCTURE CONFINING A VERTICAL OPENING Filed Aug. 23, 1963 FIG.

Inventor:

F RA NZ HOFMANN out friction.

United States Patent O FORMWORK FOR THE INSIDE SURFACE OF A WALL STRUfiTURE CONFINING A VERTICAL OPENING Franz Hofmann, Schoenberg 7, Post Regau, Oberosterreich, Austria Filed Aug. 23, 1963, Ser. No. 303,987 3 Claims. (Cl. 249-) Wells or shafts required for various purposes in structural engineering are lined in most cases with concrete and the formwork is often made from boards with suitable uprights, cross struts and the like. Such a formwork involves a relatively large amount of work as well as losses of formwork material due to cutting and damage. Because many shafts or wells have similar dimensions, it has also been proposed to use a formwork of sheet metal, which can be utilized several times. These known formwork structures consist of a composite sheet metal shell, which is very thin, so that it is flexible, and which is articulated by straps to nuts carried by a central screw, which may be provided with left-hand and right-hand screw threads. When the screw is rotated from above, the nuts are axially displaced so that the sheet metal shell is expanded or, for release from the wall of the shaft or Well, is contracted. All these designs have the disadvantage of being relatively complicated and expensive and being liable to be deranged by the rough usage on a building site because they comprise a large number of articulated joints and the shell may also consist of several parts. Finally, a structure for use as an inner form- Work for chimneys has been disclosed, which structure consists of a sheet metal shell, which can be pulled up by means of a stirrup applicable to the upper rim of the chimney and a screw held by said stirrup when the chimney walls have been erected. Such a structure, however, can be used only for a specific purpose and has the disadvantage that the prismatic sheet metal shell can hardly be removed from the chimney wall.

It is an object of the invention to eliminate all these disadvantages and provide a formwork for the walls of shafts or wells, which formwork can be used repeatedly and distinguishes by a relatively simple, inexpensive and reliable design and can be removed in a simple manner from the concrete wall surface of the shaft or well.

The invention is based on a formwork which comprises a sheet metal shell and a screw which is rotatable from above and is essentially characterized in that the sheet metal shell has the shape of a downwardly tapering, slender frustum of a cone or of a pyramid and is adapted to be lifted with the aid of the screw bearing on the bottom of the shaft or well. Owing to the taper of the sheet metal shell, a small lifting is sufficient to clear the sheet metal shell from the walls on all sides so that it can be lifted along the concrete wall surface of the shaft with- The sheet metal shell need not be composite nor be made from very thin sheet metal and the use of straps for expanding the shell as well as of leftand right-hand screw threads is not required so that a relatively simple and robust structure is obtained.

A particularly useful formwork will be obtained according to the invention if the sheet metal shell, which is provided at the top with handles in known manner, has adjacent to its lower end a transverse wall or the like, which carries a fixed, preferably centrally arranged nut for the screw and the latter is rotatably mounted in a bottom plate and the sheet metal shell has additional transverse partitions or the like, if desired, for stiffening purposes and for guiding the screw. The bottom plate prevents the screw from digging into the earth without lifting the sheet metal shell. The rotatable mounting of the screw in the bottom plate prevents the latter from following the rotation of the screw. The transverse partitions in the shell ensure a good guidance of the screw and at the same time stiffen the shell. When the shell has ben released, it can easily be gripped and pulled up with the aid of the handles at its upper end.

An embodiment of the invention is shown by way of example on the accompanying drawings, in which FIG. 1 is a vertical sectional view showing a formwork for a shaft or well and F168. 2 and 3 are transverse sectional views taken on line A-B of FIG. 1 through quadrangular and circular sheet metal shells, respectively.

The formwork comprises a downwardly tapering sheet metal shell 1, which has a quandrangular (FIG. 2) or a circular (FIG. 3) cross-section so that it has the shape of a frustum of a pyramid or of a cone, respectively. Transverse partitions 2, 3, 4 are welded into the sheet metal shell 1. The lowermost transverse partition 4 carries a stationary, central nut 5, which is in threaded engagement with a threaded shaft or screw 6, which extends throughout and above the sheet metal shell and at its lower end is rotatably connected to a bottom or abutment plate 7 to be placed on the bottom of the well or shaft. The top end of the screw 6 has the shape of a fork, which serves as a handle for rotating the screw. A cross-bar or the like may be inserted into the fork to provide for a larger leverage. The transverse partitions 2 and 3 serve for guiding the spindle and at the same time for stiffening the shell. The sheet metal shell carries at its top two handles 8, at which it can be gripped and pulled out of the well or shaft when the shell has been released and lifted from the back-filled concrete 9 by a rotation of the screw 6. It is recommendable to apply to the outside of the shell an agent which reduces the adherence to the concrete.

I claim:

1. A mold for the production in situ of tubular linings of cementitious materials, comprising, a tubular sheet metal shell having a central longitudinal axis of symmetry and of regular geometrical form in planes normal to said axis, said shell tapering uniformly upwardly and outwardly from its first lower end to its second upper end, first and second partition plates fixed, respectively, adjacent the lower and upper ends of and within said shell, a third partition plate secured to and within said shell intermediate said first and second partition plates, each said plate having its peripheral edges integrally secured with the contiguous inner wall of said shell, at a plurality of locations equiangularly spaced about said axis, a nut fixed with said lower partition on said axis, a shaft extending in and along said shell in coincidence with said axis and having its lower end portion threadedly engaging said nut, said shaft extending through and having bearing support in said second and third plates, an abutment plate sized and shaped for a loose fit within the lower end of said shell below said first partition plate, a thrust bearing between the lower end of said shaft and said abutment plate, said bearing normally connecting said abutment plate against separation from said shaft while permitting relative rotation therebetween, means connected with the upper end of said shaft, above the level of the upper end of said shell, for effecting rotation of said shaft and thereby, relative axial translation of said shaft and abutment plate relatively to said shell.

2. The mold of claim 1, said shell being the frustum of a right cone, said partition plates being generally square plates with corners truncated on arcs of radii equal to that of said shell at the respective common cross sectional planes thereof, the edges of said truncations being rigidly attached to the contiguous inner surface of the shell.

3. The mold of claim 1, said shell being the frustum bf 21 right py 'amid, said partition plates, being generally 960,909 6/ 10 Harris 2 5-121 square with corners tfu'n'cated'foi' a srndoth fit in and be- 974,350 11/ 10 Br atton 25-1281 tween the sides of said she'll at the respective common 1,171,579 2/ 16 Atterbnjry 2 25-1281 cross sectionalplanes, the edges f saidtrqncation being 1,198,087 9/16 Venable 25-128 figidly attached to the inner surface of the shell, 5 1,391,988 9/21 Zents 25-1281 V i 7 1,631,154 6/27 Poetz 28-128.! R f r es Cited y the Examiner V V 2,013,918 9/35 Kelleher 2s4 9s UNITED STATES'PATENTS 7 V. 774 007 11 04 Tinstman 25 12 1 MICHAEL R D nmary Examiner 867,129' 9 /07 Hartetal. 25-128.1 T I E B 

1. A MOLD FOR THE PRODUCTION IN SITU OF TUBULAR LININGS OF CEMENTITIOUS MATERIALS, COMPRISING, A TUBULAR SHEET METAL SHELL HAVING A CENTRAL LONGITUDINAL AXIS OF SYMMETRY AND OF REGULAR GEOMETRICAL FORM IN PLANES NORMAL TO SAID AXIS, SAID SHELL TAPERING UNIFORMLY UPWARDLY AND OUTWARDLY FROM ITS FIRST LOWER END TO ITS SECOND UPPER END, FIRST AND SECOND PARTITION PLATES FIXED, RESPECTIVELY, ADJACENT THE LOWER AND UPPER ENDS OF AND WITHIN SAID SHELL, A THIRD PARTITION PLATE SECURED TO AND WITHIN SAID SHELL INTERMEDIATE SAID FIRST AND SECOND PARTITION PLATES, EACH SAID PLATE HAVING ITS PERIPHERAL EDGES INTEGRALLY SECURED WITH THE CONTIGUOUS INNER WALL OF SAID SHELL, AT A PLURALITY OF LOCATIONS EQUIANGULARLY SPACED ABOUT SAID AXIS, A NUT FIXED WITH SAID LOWER PARTITION ON SAID AXIS, A SHAFT EXTENDING IN AND ALONG SAID SHELL IN COINCIDENCE WITH SAID AXIS AND HAVING ITS LOWER END PORTION THREADEDLY ENGAGING SAID NUT, SAID SHAFT EXTENDING THROUGH AND HAVING BEARING SUPPORT IN SAID SECOND AND THIRD PLATES, AN ABUTMENT PLATE SIZED AND SHAPED FOR A LOOSE FIT WITHIN THE LOWER END OF SAID SHELL BELOW SAID FIRST PARTITION PLATE, A THRUST BEARING BETWEEN THE LOWER END OF SAID SHAFT AND SAID ABUTMENT PLATE, SAID BEARING NORMALLY CONNECTING SAID ABUTMENT PLATE AGAINST SEPARATION FROM SAID SHAFT WHILE PERMITTING RELATIVE ROTATION THEREBETWEEN, MEANS CONNECTED WITH THE UPPER END OF SAID SHAFT, ABOVE THE LEVEL OF THE UPPER END OF SAID SHELL, FOR EFFECTING ROTATION OF SAID SHAFT AND THEREBY, RELATIVE AXIAL TRANSLATION OF SAI SHAFT AN ABUTMENT PLATE RELATIVELY TO SAID SHELL. 